Production of fast dyeings and printings by means of ester salts of leuco vat-dyestuffs



Patented Mar. 11, 1941 PRODUCTION OF PRINTINGS BY rAs'r DYEINGS AND MEANS OF ESTER SALTS 0F LEUCO VAT-DYESTUFFS Georges de Niederhiiusern,

Christian Hofmann, Basel,

Erich Escher, and

Switzerland. as-

signors to the firm Durand & 'Huguenin S. A, Basel, Switzerland No Drawing. Application February 24, 1938,

Serial No. 192,426.

8 Claims.

It is known that ester salts of leuco vat-dyestuffs exhibit different behaviours towards acid oxidising agents. Whilst some can be developed by mild oxidising agents and even at a low temperature others require for developments a more energetic oxidising agent and in some cases a higher temperature. In other words the oxidation potential necessary for the development of a dyeing from an ester salt varies greatly in the case of different ester salts.

On the other hand it is a fact that some vatdyestufls produced on the fibre by oxidation of the ester salts are easily over-oxidised by the oxidising agent by which the dyeing is developed. The result of this is that the shade deviates substantially from that which is desired.

It will be apparent from the foregoing that difflculty will be experienced for example when it is desired to develop simultaneously on one and the same material two ester salts of which one is easily developed and in some cases may be sensitive to over-oxidation whilst the other is developed with difliculty. If the oxidation is suited to the first ester salt the second will be lnsuflicientiy developed; if it is suited to the second ester salt the first will be over-oxidised.

Proposals for avoiding such difilculties have already been made for instance in U. 8. Patents Nos. 1,779,305'and 1,874,274, in British Patents Nos. 389,156 and 426,073, and others.

According to this invention damage to dyeings of ester salts which are sensitive towards overoxidation is to a considerable extent prevented and on the other hand the development of other ester salt dyeings which require a more energetic oxidation is not hindered if the development by acid oxidation is conducted in the presence of a protective substance, which is easily converted by oxidation into a compound of the quinone series, selected from the group consisting of aromatic polyoxy compounds, amino-oxy compounds and the sulphonic or carboxylic acids thereof. Among the compounds coming into consideration for the purpose of the invention, there are men'- tioned for example hydroquinone, 1:4-naphthohyd'roquinone, l-amlno-2-naphthol-4-sulphonic acid, pyrocatechin, further members of the tannic acid group consisting of tannin, gallic aci and pyrogallol.

Meta-dioxy compounds, for example resorcin, are not within the scope of the invention.

It may be considered remarkable that the quantity of theprotectivefagent used need bear no'stoichiometric relationship to the quantity of the excess of oxidising agent present in the bath,

In Germany March 1,

that is to say the quantity ing has been developed. For attaining the desired effect, that is to say a normal development of the dyeing, it is as a rule sufilcient to use only a fraction of that quantity of the protective agent which might be expected to be necessary having regard to the quantity of oxidising agent used.

The process of the invention accordingly oilers certain advantages as compared with those hitherto known.

Substances similar to ent invention have already been protecting the fibres fromv damage in dyeing cellulose fibres with vat-dyestuifs. The effect in that case lies in anotherdirection and from it I the effect attained by the present invention could not be foreseen.

The invention is suitable both for dyeing and for printing cellulose fibres or fibres of regenerated cellulose.

The following examples illustrate the invention, the parts being by weight:

present after the dyethose used in the presproposed for 10 parts of a fabric of matted viscose artificial silk are pre-dyed for /4 hour in a bath maintained at a temperature of 20 C. and prepared by dissolving 0.3 part of sodium l-propylnaphthaienesulphonate,

0.09 part of the leuco ester salt of the vat-dyestufl described in Example 1 ofv British specification N0. 24,604/08,

7.5 parts of calcined sodium sulphate in 300 parts of water.

The material is wrung out and without an intermediate drying the dyeing is developed in a fresh bath containing per 1000 parts 36 parts of sulphuric acid of 96 per cent strength, 1 part of sodium nitrite and 0.5 part of hydroquinone. The oxidation is continued for /4 hour in the case of one batch of material at 20 C..and in the case of another batch at C.

The material is then treated in a lukewarm solution of sodium carbonate, thoroughly rinsed and finally soaped for 15 minutes at -90 C. in a bath containing 5 grams oi Marseilles soap per litre.

There is practically no difference between the two olive-green dyeings obtained, namely (1) that developed "at 20 C. and (2) that developed at 60 C. If the hydroquinome omitted dyeing 1 would be dullowing to slight over-oxidation and dyeing 2 would be still duller owing to stronger over-oxidation.

' Example 2 A padding solution is prepared of the following composition: a

' Parts Sodium salt of the tetra-sulphuric acid ester of tetrahydrodichloro- 1 :2 :2 1'-dianthraquinoneazine I 5 Sodium 1-propylnaphthalene14-su1phonate- 1 Hydroquinone 3 Sodium nitrite 10 made up with watt; to 1000 parts. 1

Bleached cotton goods are Padded .with this solution in a 3-roller foulard at 5060 C. and then dried in a hot flue. The dyeings are developed for 15 minutes in a jigger in a bath'containmg per litre 36 grams of sulphuric acid of 96 per cent strength in the case of one batch of goods at 20 C. and in the case of another batch at 60 C.

' The goods are then rinsed and the last residues of acid are neutralized by means of a lukewarm' sodium carbonate bath; finally the goods are soaped for 4 hour in a boiling bath containing 5 grams of Marseilles soap per litre.

There is practically no diiference between the dyeings developed at 20 C. and at C. respectively. If however the hydroquinone be omitted a normal shade would only be obtained by development at 20 C.,v whilst development at 60 C. would lead to a shade which is greener and duller owing to over-oxidation.

A similar result is obtained if the hydroquinone be added to the soap bath instead of to the pad- .ding bath.

Example 3 Neutral tragacanth thickening 80/1000 50 Calclnated sodium carbonate 1 Sodium nitrite 7 o made up with water to 1000 parts.

Bleached cotton is padded in a 3-roller foulard with this solution at 50 C. and then without an intermediate drying the dyeing is developed in a jigger.

The developing bath contains per litre of liquor 36 grams of sulphuric acid of 96 per cent strength and 0.1 gram of hydroquinone. The development is allowed to proceed for 15 minutes at 20 C. The material isthen rinsed, neutralized in a lukewarm sodium carbonate bath, again rinsed and finally soaped for V hour in a boiling bath containing 5 grams of Marseilles soap per litre.

There is obtained -a pure olive-green dyeing. If the addition of hydroquinone were omitted there would be obtained even under the mild oxidation conditions of 20 C. dyeings which are dull owing to over-oxidation.

Example 4 20 parts of bleached. cotton goods are treated for hour in a Jigger at 20 C. with 100 parts of After this treatment the material is wrung out. It is. not necessary to dry it. The dyeing is de. veloped by treatment for 4 hour at 60 C. in a fresh bath containing per 100 parts of liquor 3.6

parts of sulphuric acid of 96 per cent strength, 0.1 part of sodium nitrite and 0.05 part of tannin. The goods are then thoroughly rinsed, neutral ized in a lukewarm sodium carbonate bath and finally soaped for 30 minutes in a boiling soap bath containing 0.5 part of Marseilles soap per 100 parts. The dyeing so obtained has a pure blue shade. If the addition of tannin to the oxidation bath is omitted, the, procedure being otherwise the same, there is obtained a dull greenish shade due to oxer-oxidation:

Example 5 A cotton fabric is printed with the following printing paste:

. 1 Parts Sodium salt of the tetra-sulphuric acid ester of tetrahydrodichloro-1:2-2' l'-dianthraquinoneazine 3 Water 35 Neutral starch tragacanth thickening 60 Sodium carbonate solution (10 per cent) 2 The material is dried and developed for 8 secends at 0. man oxidation bath containing per 1000 parts:

i The dyeing is thus developed normally and fully whereas without the addition of hydroquinone there would be obtained under otherwise the same conditions a greenish dull blue resulting from over oxidation.

Example 6 A material printedwi-th the printing paste described in Example 5 is developed for 15' seconds in a developing bath containing per litre 36 grams .of sulph ric acid of 96 per cent strength, 20

grams of nitrite and 0.5 gram of 'pyrocatechin. The result is the same as that obtained according to Example 5.

Instead of the protective agents named in the foregoing examples the following may be used with similar results: pyrogallol, gallic acid, paraaminophenol, -N-methyl-para-aminophenol, 1 :4- 1

naphthohydroquinone, l-amino 2 naphthol-4- sulphonic acid and others.

The invention is applicable with advantage in th development of ester salts of the following vat-dyestuffs: indigo, monobromindigo, N-dihydro-1:2-2:l'-diantln'aquinoneazine, the dyestuff from a-isatinanilide and l-methyl-7z8- oxybenzocarbazole and others.

Aqueous solutions of ester salts of leuco vatdyestufis as used in this and other dyeing and printing processes frequently suffer from the inconvenience that they become oxidised by atmos- I pheric oxygen under the influenceof daylight, especially direct sunlight, the insoluble vat-dyestuif being precipitated. This inconvenience is present in the case of all articles which become saturated with such solutions, for example the vessels and wooden parts of dyeing and printing apparatus. This inconvenience can be counteracted to a large extent by adding to such solutions small proportions of the protective agents hereinbefore referred to such as hydroquinone. Under these circumstances the protective agents also exert their action in preventing or moderating oxidation.

What we claim is:

1. A process for dyeing or printing with ester salts of leuco vat-dyestuffs, wherein the dyeing or print is developed by acid oxidation in the presence of a protective substance, which is easily converted by oxidation into a compound of the quinone series, selected from the group consisting of aromatic polyoxy amino-oxy, sulphonated and carboxylated aromatic polyoxyand amino-oxy compounds.

2. A process for dyeing or printing with ester salts of leuco vat-dyestufis, wherein the dyeing or print is developed by acid oxidation in the presence of a hydroquinone compound.

3. A process for dyeing or printing with ester salts of leuco vat-dyestufis, wherein the dyeing or print is developed by acid oxidation in the presence of hydroquinone.

4. A process for dyeing or printing with ester salts of leuco vat-dyestuffs, wherein the dyeing or print is developed by acid oxidation in the presence of pyrocatechin.

5. Padding solutions suitable for dyeing with ester salts of leuco vat-dyestuii's, containing besides the ester salt a protective substance which is easily converted by oxidation into a compound of the quinone-series, selected from the group consisting of aromatic poly-oxy-, amino-oxy-, sulphonated and carboxylated aromatic polyoxy-and amino-oxycompounds.

6. A padding solution suitable for dyeing with ester salts of leuco vat-dyestuffs, containing besides an ester salt of a leuco vat-dyestufl, hydroquinone.,

7; Printing pastes suitable for printing with ester salts of leuco vatdyestufls, containing besides the ester salt a protective substance which is easily converted by oxidation into a compound of the quinone series, selected from the group consisting of, aromatic poly-.oiw-, amino-oxy-, sulphonated and carboiwlated aromatic polyoxyand amino-oxy compounds.

8. A printing paste suitable for printing with ester salts of leuco vat-dyestufl's. containing besides an ester salt of a leuco vat-dyestuii', hydroquinone.

GEORGES n: NIEDERHAUSERN.

ERICH ESCHER. CHRISTIAN HOFMANN. 

